Stephanie belongs to a PPO that has a $1,000 deductible. The deductible applies only if Stephanie meets with doctors outside her network. There is no co-payment. Stephanie incurred a bill of $2,000 when she met with an out-of-network specialist for a thyroid problem. She owes $1,400 out of pocket for the bill because the PPO will pay $600 after Stephanie's deductible. What is the co-insurance clause of the PPO that Stephanie belongs to?